As a compound having a PRS inhibitory activity, febrifugine derivatives represented by halofuginone can be mentioned. They were known as antimalarial drugs in the past and application thereof to cancer, fibrosis, inflammatory diseases and the like has been expected in recent years (non-patent documents 1, 2). As for halofuginone, for example, an anti-cancer action against osteosarcoma and colorectal cancer has been reported (non-patent documents 3, 4). PRS is one of the aminoacyl tRNA synthases, involved in the synthesis of proteins, and is suggested to be related to cancer (non-patent document 5).